We have recently developed flow cytometric procedures for hormone receptor expression in human breast and prostate tumors. Decisive studies on the heterogeneity of marker expression in human tumors have been limited by the difficulty of separating the aneuploid populations from the diploid population in the tumor. A new flow cytometric method of identifying aneuploid sub populations based on the Coulter volume principle has been developed which will remove this limitation. Distortions of the shape and size of the nucleus along with staining variations have been recognized as a hallmark of cancer since the work of Virchow. Directly measuring these distortions of the nucleus by Coulter volume is now possible with the IFC flow cytometer. These measurements not only identify aneuploid populations but may provide novel biological information of diagnostic value. The purpose of this Phase I study is to combine these two techniques by adding a second optical channel to the IFC cytometer to allow simultaneous three parameter gated analysis of DNA, electronic nuclear volume and hormone receptor expression in human tumors, and determine the correlation between aneuploidy, cell cycle distribution and hormone marker expression in human breast and prostate tumors. PROPOSED COMMERCIAL APPLICATIONS: According to the American Cancer Society, there will be 175,000 new cases of invasive breast cancer, and 179,000 new prostate cancers diagnosed this year. Tumor sizes especially in breast cancer are becoming smaller. This provides a significant market for a hormone expression test which give an accurate value from the aneuploid population in small tissue samples or fine needle aspirates.